The Robotics Institute Carnegie Mellon University has developed a pair of autonomous robots which will shortly be moving through miles of pipes at the former uranium enrichment plant of the U.S. Department of Energy, in Piketon, Ohio, to detect uranium deposits on pipe walls.
The improved ability of the CMU robot in evaluating radiation levels with higher accuracy from the inner side of the pipe, in comparison with external methods, has been demonstrated. Apart from minimizing the labor costs, the robot’s use considerably decreases risks to workers who otherwise must carry out external evaluations by hand, dressed in protective gear and using scaffolding or lifts to reach elevated pipes.
DOE officials predict that the robots could save several million dollars of cost in finishing the characterization of uranium deposits at the Portsmouth Gaseous Diffusion Plant in Piketon, and maybe save 50 million dollars at a similar uranium enrichment plant in Paducah, Kentucky.
“This will transform the way measurements of uranium deposits are made from now on,” estimated William “Red” Whittaker, a robotics professor and director of the Field Robotics Center.
Two technical papers related to the robot will be presented by Heather Jones, senior project scientist, at the Waste Management Conference in Phoenix, Arizona, on March 21, 2018. A demonstration of a prototype of the robot will also be demonstrated by CMU during the conference.
CMU is developing two such robots, known as RadPiper, and will hand over the production prototype units to DOE’s vast 3778-acre Portsmouth site in May 2018. An innovative “disc-collimated” radiation sensor developed by CMU is incorporated into RadPiper. The CMU researchers, headed by Whittaker, started working on the project in 2017. The researchers worked in close collaboration with DOE and Fluor-BWXT Portsmouth, the decommissioning contractor, to develop a prototype on a tight schedule and investigate it at Portsmouth in the fall of 2017.
The plant, which started its operations in 1954 and synthesized enriched uranium, including weapons-grade uranium, has been closed since 2000. The floor space of the plant is 10.6 million square feet, making it the largest facility of DOE under roof, including three large buildings that house enrichment process equipment with a size equivalent to that of 158 football fields. The process buildings include over 75 miles of process pipe.
Detecting the uranium deposits, which is mandatory before decontamination, decommissioning, and demolition of the facility by DOE is an extremely challenging task. In the last three years, human crews have carried out over 1.4 million manual evaluations of components process and piping in the first process building and are about to declare it “cold and dark.”
With more than 15 miles of piping to be characterized in the next process building, there is a need to seek a smarter method. We anticipate labor savings on the order of an eight-to-one ratio for the piping accomplished by RadPiper.
Rodrigo V. Rimando, Jr., Director of Technology Development - DOE’s Office of Environmental Management
Although RadPiper is being used, in some components, nuclear deposits have to be manually identified.
At first, RadPiper will function inside pipes measuring 30 and 42 inches in diameter and will quantify radiation levels in each foot-long pipe segment. The segments containing potentially dangerous amounts of uranium-235 will be eliminated and decontaminated, where uranium-235 is the fissile isotope of uranium used in weapons nuclear and reactors. The huge majority of the piping in the plant will remain intact and will be knocked down safely together with the remaining facility.
The tetherless robot is positioned on top of a pair of flexible tracks and driven through the pipe at a constant speed. According to Jones, Even though the pipe is in straight sections, a lidar and a fisheye camera are incorporated into the autonomous robot to identify obstructions, such as closed valves, ahead. Upon completion of a run inside the pipe, the robot automatically comes back to its launch point. Unified data analysis and report generation save the efforts of nuclear analysts in performing time-consuming computations and provides reports the same day.
For counting gamma rays, a standard sodium iodide sensor is incorporated into the disc-collimated sensing instrument of the robot. The sensor is located between two large lead disks, which block gamma rays from uranium deposits resting away from the 1-foot section of pipe under investigation at any given point in time. Whittaker stated that CMU has filed for a patent on the instrument.
The Robotics Institute and Whittaker have ample experience in using robots inside nuclear facilities, such as the design and construction of robots to assist in cleaning up the crippled Chernobyl reactor in Ukraine and the damaged Three Mile Island reactor building in Pennsylvania.
DOE has made a payment of 1.4 million dollars to CMU to build the robots as part of what CMU terms the Pipe Crawling Activity Measurement System.
According to Rimando, apart from the Paducah and Portsmouth plants, robots can be used in other places in DOE’s defense nuclear cleanup program, which is hardly half complete. Other places at which the robots could be used are the Hanford Site in Richland, Washington and the Savannah River Site in Aiken, South Carolina.
“With at least 50 more years of nuclear cleanup to be performed, the Robotics Institute could serve as a major pipeline of roboticists for DOE’s next several workforce generations,” he further stated.